Just a quick note to say that the 54 fourth-generation inverters (M215IGs and M250s) in my system have attained an MTBF over twice that of the 42 original third-generation inverters (M190s) which were finally fully retired in October 2017:

iPlug wrote:Row 200 and row 215, (Rocklin, CA): no system changes, all original inverters as noted, still no failures.

Thanks! That brings the MTBF of the inverters in your system over 161 years.

BTW, with no failures an actual failure rate cannot be established, just a suspected lower bound. I would feel best to have at least five failures to establish some sort of failure rate for a given population. Even then, I find the failure rate of the original M215s in my spreadsheet to be a bit suspect since the failures are nearly all clustered around two systems near North Syracuse, NY. Outside of those two systems, the original M215s have a very impressive record.

Simply put, calculating MTBF is a bit of a messy business. But as time goes on the data here should prove to be more and more useful, particularly if the fourth-generation inverters prove to have a long operating life.

1) Your system stopped reporting on October 20. Did your Envoy die?2) Enlighten lists 37 inverters even though you have 35 in your array. Have you had 2 M190s die?

Even without any response from Tony, I have decided to record two M190 failures and one Envoy failure for his system. The signature of having additional inverters introduced to the system seems like a clear indication of failures. What it DOESN'T tell me is what replaced the M190s. This updated brings the MTBF for the M190s in Tony's system to 118 years. That is much better than most M190 systems out there.

I will use this approach with other systems in the spreadsheet, but I will NOT update the monitored date if the number of inverters shown matches how many are in the array. In that case, there are really three possibilities: 1) No failures, 2) There were failures but no inverters have been replaced, or 3) There were failures, the inverters were replaced, and Enphase properly removed the old inverters from Enlighten.

In looking around the spreadsheet for other signatures like I see with Tony's system, I ran across a large D380-based system in row 26 where the owners had the ENTIRE system replaced and upgraded in August 2016. I have no idea what possessed Enphase to think that putting two M190s into a single package would be a good idea. Understanding the impact of failures dictates that the D380 had to have a failure rate significantly higher than the M190s. Perhaps the M190 failures had not yet kicked in at the time.

Thanks! Updated. The M250s will cross over 400 device-years within the next few months and we still have yet to record a single failure.

This week marks a year since I have experienced a failure of any of the inverters in my system: an M215IG which failed on January 25, 2017. Outside of the four failures of M190IGs (which are not properly grounded through their adapter cables) that is the only failure of an "integrated ground" fourth-generation Enphase inverter connected (properly connected using Engage) that I know about. That is after 500 total device-years of operation of M215IGs and M250s.

This week also marks 100 device-years of operation of fourth-generation Enphase inverters in my system: M190IG: 2.5 device-years, M215IG: 69.6 device-years, M250-60: 24.7 device-years, and M250-72: 3.2 device-years. Given the one failure of an M215IG, that puts the MTBF for fourth-generation inverters in my system at 100 years. The oldest fourth-generation inverter has been on my roof for a bit over 3.5 years now. Hopefully it will be many years before a few more units fail, thus establishing an accurate MTBF number for the fourth-generation inverters in this system.

By comparison, the original M190s (third generation) racked up about 249 devices-years before being replaced and experienced 6 failures over 6.8 calendar years, giving an MTBF of about 41 years. It will be about three more years before I have that much calendar- and device-time on the fourth-generation units.

Would anyone else like to provide an update on your Enphase system? TIA!

RegGuheert on November 27, 2017 wrote:These new inverters went into service on October 23, 2017. Over one month later, I am still seeing the "Cycles Skipped" messages associated with large power dropouts. It is not always the same inverters showing this issue.

The new 72-cell M250 inverters have now been producing for over three months and these "Cycles Skipped" messages are still happening. Yesterday there were two different instances involving a total of four of the twelve new inverters.

It's no big deal in terms of production because the inverters recover fairly quickly. But it is odd to see these malfunctions so regularly. My only real concern is that there could be some additional stress induced during these incidents that might eventually damage these inverters.

BTW, on Thursday I reached a milestone of one year since the last microinverter failure (an M215IG) in my system. Let's hope this stretch continues for many more years!